1. Field of the Invention
The invention relates to a fire resistant yarn and to a method of preparing a fire resistant yarn. The invention also relates to a fabric which includes the fire resistant yarn. The invention has particular applicability in the formation of fire resistant fabrics for applications such as upholstery, mattress and pillow ticking, bed spreads, pillow covers, draperies or cubicle curtains, wallcoverings, window treatments and baby clothing.
2. Description of the Related Art
It is well known in the textile industry to produce fire resistant fabrics for use as upholstery, mattress ticking, panel fabric and the like, using yarn formed of natural or synthetic fibers, and then treating the fabric with fire retarding chemicals. Conventional fire retarding chemicals include halogen-based and/or phosphorus-based chemicals. Unfortunately, such treated fabric is heavier than similar types of non-fire retardant fabrics, and further has a limited wear life. Also, this type of fabric typically melts or forms brittle chars which break away when the fabric is burned, and exposes the foam of a composite chair, mattress or panel fabric system. The exposed foam then acts as a fuel source.
It is also known to form fire resistant fabrics of fire resistant, relatively heavy weight yarns in which a low temperature resistant fiber is ring spun around a core of continuous filament fiberglass. However, this type of ring spun yarn has torque imparted thereto during the spinning process and is very lively. Because of the lively nature of the yarn, it is necessary to ply "S" and "Z" ring spun yarns together so that the torque and liveliness in the yarn is balanced in order to satisfactorily leave or knit the yarn into the fabric, without experiencing problems of tangles occurring in the yarn during the knitting or weaving process. This plying of the "S" and "Z" yarns together results in a composite yarn which is so large that it cannot be used in the formation of fine textured, lightweight fabrics. In some instances, the fiberglass filaments in the core protrude through the natural fiber sheath. It is believed that the problem of protruding core fibers is associated with the twist, torque and liveliness being imparted to the fiberglass core during the ring spinning process.
It is the current practice to produce coated upholstery fabrics by weaving or knitting a substrate or scrim of a cotton or cotton and polyester blend yarn. This scrim is then coated with a layered structure of thermoplastic polyvinyl halide composition, such as polyvinyl chloride (PVC). This coated upholstery fabric has very little, if any, fire resistance and no flame barrier properties. In addition to the coating chemical having a limited shelf life, the chemical coatings are disadvantageous in that they pose a safety hazard in case of contact with skin.